The present invention relates to an air cycle air-conditioning apparatus employing air as a refrigerant for effecting heating and, more particularly, to a heating capacity improving scheme.
There has been conventionally known a refrigerating apparatus of the air cycle type employing air as a refrigerant. One example of such an air cycle refrigerator is shown in xe2x80x9cJAR HANDBOOK, FUNDAMENTALS, Fourth Editionxe2x80x9d, published by Japanese Association of Refrigeration, pp. 45-48. Further, there is disclosed in xe2x80x9cJune Issue of the AIRAH JOURNAL (1997)xe2x80x9d, pp. 16-21, published by The Australian Institute of Refrigeration Air Conditioning and Heating a heating apparatus capable of performing heating by using an air cycle refrigerator as a heat source. Hereinafter, a description of this heating apparatus will be given below.
As shown in FIG. 3, the heating apparatus has a heat source-side system (a) and an exhaust heat-side system (f). The heat source-side system (a) is formed by sequential connection of a compressor (b), a first heat exchanger (c), a second heat exchanger (d), and an expansion device (e), for performing an air refrigerating cycle. On the other hand, the exhaust heat-side system (f) is formed by sequential connection of the second heat exchanger (d), a humidifier (g), and the first heat exchanger (c).
In such an arrangement, when the compressor (b) is driven in the heat source-side system (a), exhaust air for ventilation is compressed in the compressor (b). The compressed air flows through the first heat exchanger (c) and then through the second heat exchanger (d), undergoes expansion in the expansion device (e), and is expelled to outside the room. On the other hand, in the exhaust heat-side system (f), supply air for ventilation from the outside of the room flows through the second heat exchanger (d), the humidifier (g), and the first heat exchanger (c) in that order, during which the supply air is heated by heat exchange with the compressed air in the heat source-side system (a) in both the heat exchangers (d, c) and humidified in the humidifier (g). Then, the heated, humidified supply air is supplied into the room for effecting heating.
However, the heating apparatus stated above suffers problems such as insufficient heating capacity and therefore fails to properly provide room heating. This problem will be described. In the heating apparatus, only the exhaust air for ventilation is let to flow to the heat source-side system (a). The amount of such ventilation is determined by, for example, the number of people present in the room (for example, 4 m3/hr for every 1 m2 of floor space), independent of the heating load. And, in most cases, only a flow of exhaust air for ventilation is insufficient for the purpose of achieving a heating capacity in proportional to the heating load. However, it is impossible for the heating apparatus to provide a flow of air at increased flow rates to the heat source-side system (a), therefore giving rise to lack of heating capacity.
Bearing in mind such drawbacks, the present invention was made. Accordingly, an object of the present invention is to ensure that an air-conditioning apparatus which performs heating by making utilization of an air cycle provides sufficient heating capacity.
According to an arrangement of the present invention, together with exhaust air for ventilation, air from the outside of a room (outdoor air) is let to flow to a heat source-side system which generates heat by making utilization of an air cycle, for achieving an increased air flow rate in the heat source-side system.
More specifically, the present invention provides a first solution means that is directed to an air-conditioning apparatus which heats room air by an air cycle employing air as a refrigerant for performing air-heating. The air-conditioning apparatus of the first solution means comprises a compressor (21) which draws in air from the outside and the inside of a room for compressing the drawn air, a heating means (30) which heats air for conditioning formed of at least air from the room by heat exchange with the compressed air compressed by the compressor (21), and an expansion device (23) which provides expansion of the compressed air which has undergone the heat exchange in the heating means (30), wherein low-temperature air, expanded and lowered in temperature in the expansion device (23), is expelled to the outside of the room, whereas the conditioning air heated by the heating means (30) is supplied into the room.
Further, the present invention provides a second solution means according to the first solution means, wherein the air that is drawn into the compressor (21) from the inside of the room is exhaust air that is expelled from the inside of the room for ventilation.
Further, the present invention provides a third solution means according to the first solution means or the second solution means, wherein the conditioning air is formed of air from the room and supply air that is supplied from the outside to the inside of the room.
Further, the present invention provides a fourth solution means according to any one of the first to third solution means, the fourth solution means including a demoisturizing means (22) which has a separation membrane, the separation membrane being formed such that water vapor in the air is allowed to pass therethrough from a high partial pressure of water-vapor side to a low partial pressure of water-vapor side thereof, for separation of water vapor contained in the compressed air without causing the water vapor to undergo condensation.
Further, the present invention provides a fifth solution means according to the fourth solution means, wherein the separation membrane is composed of a polymeric membrane and formed so as to allow water vapor to pass therethrough by water-molecule diffusion in the membrane.
Further, the present invention provides a sixth solution means according to the fourth solution means, wherein the separation membrane has a large number of pores having a size equal to a molecule free path and is formed so as to allow water vapor to pass therethrough by water-molecule capillary condensation and diffusion.
Further, the present invention provides a seventh solution means according to any one of the fourth to sixth solution means, the seventh solution means including a depressurizing means (36) which provides depressurization of one of the sides of the separation membrane in the demoisturizing means (22) so as to ensure a difference in partial pressure of water-vapor between both the separation membrane sides.
Further, the present invention provides an eighth solution means according to the seventh solution means, wherein a part or all of moisture separated from the compressed air by the demoisturizing means (22) is supplied to the low-temperature air from the expansion device (23).
Further, the present invention provides a ninth solution means according to the seventh solution means, the ninth solution means including a moisturizing means (42) which supplies moisture separated from the compressed air by the demoisturizing mans (22) to the conditioning air in the heating means (30).
Further, the present invention provides a tenth solution means according to any one of the fourth to seventh solution means, wherein a part or all of moisture separated from the compressed air by the demoisturizing means (22) is supplied, together with the conditioning air, into the room.
Further, the present invention provides an eleventh solution means according to any one of the fourth to sixth solution means, wherein the demoisturizing means (22) is formed so that one of surfaces of the separation membrane is brought into contact with the compressed air whereas the other of the surfaces is brought into contact with the conditioning air, whereby water vapor contained in the compressed air will travel to the conditioning air.
Further, the present invention provides a twelfth solution means according to any one of the first to eighth solution means, the twelfth solution means further comprising a moisturizing means (42) which supplies moisture to the conditioning air in the heating means (30).
Finally, the present invention provides a thirteenth solution means according to the ninth solution means or the twelfth solution means, wherein the moisturizing means (42) supplies moisture to the conditioning air through a moisture permeable membrane.
In the first solution means, the compressor (21) draws in air from the outside and the inside of a room. In the compressor (21), the drawn air is compressed, thereby changing to high-temperature, high-pressure, compressed air. This compressed air is subjected to heat exchange with air for conditioning in the heating means (30). Then, the conditioning air heated by the heating means (30) is supplied into the room for effecting heating. On the other hand, the post-heat exchange compressed air is expanded in the expansion device (23) and changes to low-temperature air, thereafter being expelled to the outside of the room.
Further, in the second solution means, exhaust air for ventilation is drawn into the compressor (21). That is, the operation of heating is performed making utilization of the exhaust air.
Further, in the third solution means, supply air is heated together with room air by the heating means (30) and thereafter supplied into the room.
Further, in the fourth solution means, the demoisturizing means (22) removes moisture from the compressed air compressed by the compressor (21). At that time, the demoisturizing means (22) is provided with a specified separation membrane, so that the moisture in the compressed air is separated from the compressed air in the form of water vapor.
Further, in the fifth or sixth solution means, the separation membrane is formed by a given process so that it allows water vapor to pass therethrough.
Further, in the seventh solution means, depressurization provided by the depressurization means (36) ensures a difference in partial pressure of water-vapor between both the sides of the separation membrane. That is, one surface of the separation membrane comes into contact with the compressed air and the other surface thereof is depressurized by the depressurizing means (36). Accordingly, the partial pressure of water-vapor of the other surface of the separation membrane is held lower than that of the compressed air.
Further, in the eighth solution means, moisture separated from the compressed air by the demoisturizing means (22) is expelled to the outside of the room, together with low-temperature air.
Further, in the ninth solution means, moisture separated from the compressed air by the demoisturizing means (22) is supplied to air for conditioning by the moisturizing means (42). At that time, the moisturizing means (42) provides a supply of moisture to the conditioning air which is being heated in the heating means (30).
Further, in the tenth solution means, moisture separated from the compressed air by the demoisturizing means (22) is supplied to air for conditioning and delivered, together with the conditioning air, into the room for room humidification.
Further, in the eleventh solution means, one surface of the separation membrane is brought into contact with the compressed air whereas the other surface thereof is brought into contact with the conditioning air. Accordingly, in a running condition that the conditioning air is lower in partial pressure of water-vapor than the compressed air, moisture in the compressed air travels to the exhaust air without any external action.
Further, in the twelfth solution means, the moisturizing means (42) provides a supply of moisture to the conditioning air. At that time, the moisturizing means (42) supplies moisture to the conditioning air which is being heated in the heating means (30).
Finally, in the thirteenth solution means, moisture is gradually supplied, through a specified moisture permeable membrane, to the exhaust air by the moisturizing means (42).
In accordance with the above-stated solution means, the compressor (21) draws in air not only from the inside but also from the outside of a room, therefore ensuring a sufficient flow rate for the compressed air. That is, it is possible to ensure a flow rate for high-temperature, compressed air that exchanges heat with conditioning air in the heating means (30). Because of this, it is possible to ensure an amount of heat that is applied to the conditioning air in the heating means (30), thereby achieving a sufficient heating capacity.
Further, in accordance with the second solution means, heat held in the exhaust air for ventilation is recovered and the recovered heat is utilized to heat the conditioning air. As a result of such arrangement, it is possible to provide protection against the increase in heating load caused by ventilation.
Further, in accordance with the third solution means, a mixture of room air and supply air serves as air for conditioning. This makes it possible to supply, after heating low-temperature supply air from the outside of the room, the supply air into the room, thereby improving comfortability of the person present in the room. Furthermore, in the present solution means, the conditioning air temperature is lowered to a further extent in comparison with the case in which room air serves as conditioning air. Because of this, the compressed air temperature is further lowered by heat exchange with the conditioning air in the heating means (30). This reduces the drive input of the compressor (21), thereby providing an improved equipment efficiency, i.e., COP (coefficient of performance).
Further, in accordance with the fourth solution means, it is possible to demoisturize compressed air and then deliver it to the expansion device (23). Here, the temperature of the low-temperature air from the expansion device (23) becomes considerably low (for example, aboutxe2x80x9415 degrees centigrade). Because of this, if a large amount of moisture is held in the low-temperature air, this causes the moisture to freeze in the low-temperature air. If moisture freezing occurs in the low-temperature air, this produces the following harmful effects. That is, the moisture is emitted in a snow-like form to the outside of the room together with the low-temperature air or the moisture builds up in a passageway for blowout, resulting in clogging the passageway. On the other hand, with the present solution means, the compressed air is demoisturized and thereafter expanded, so that it is possible to perform operations without suffering from the above-described harmful effects.
Further, in accordance with the fifth or sixth solution means, it is possible to positively form the separation membrane with a specified function.
Further, in accordance with the seventh solution means, it is possible to ensure, in any running operation condition, a difference in partial pressure of water-vapor between both the sides of the separation membrane by the depressurization means (36), thereby making it possible to separate water vapor from the compressed air at all times by the demoisturizing means (22). This positively provides protection against the occurrence of harmful effects due to the freezing of moisture in the low-temperature air, as described above.
Further, in accordance with the eighth solution means, it is possible to expel water vapor separated from the compressed air to the outside of the room, together with low-temperature air. This eliminates the necessity to provide a structure for the processing of separated water vapor, thereby achieving structure simplification.
Further, in accordance with the ninth or twelfth solution means, it is possible to perform room humidification by supplying moisture to the conditioning air. In this case, when the supplied moisture evaporates, it takes away heat for latent heat from the conditioning air. Because of this, if no measurement is taken, the temperature of the conditioning air will fall. However, with the present solution means, there is provided a supply of moisture to the conditioning air in the heating means (30). Accordingly, it is possible to give, by heat exchange with the compressed air, an amount of heat for a latent heat of vaporization of the supplied moisture to the conditioning air. As a result, while maintaining the temperature of the conditioning air delivered from the heating means (30) into the room at a specified value, it is possible to perform conditioning air humidification. Particularly, in accordance with the ninth solution means, it is possible to utilize moisture separated from the compressed air by the demoisturizing means (22) for room humidification.
Further, in accordance with the tenth solution means, it is possible to utilize moisture separated from the compressed air by the demoisturizing means (22) for room humidification.
Further, in accordance with the eleventh solution means, it is possible to supply water vapor separated from the compressed air to the conditioning air in the form of water vapor. That is, when humidifying the conditioning air, no supplied moisture will be evaporated in the conditioning air. Therefore, the present solution means eliminates the necessity to supply an amount of heat for a latent heat of vaporization of the moisture to the conditioning air from the compressed air, in the heating means (30). Because of this, even when the compressed air and the conditioning air exchange the same amount of heat in the heating means (30), it is possible to heat the conditioning air to further higher temperatures. As a result, while maintaining heating capacity at high level, it is possible to perform room humidification.
Finally, in accordance with the thirteenth solution means, moisture is gradually supplied to the conditioning air, thereby ensuring that the supplied moisture is evaporated positively in the conditioning air. This therefore prevents moisture incapable of being evaporated from being emitted in the form of liquid droplets into the room, together with the conditioning air.